Initial Commit

Assets/Scripts/Systems/Items/ItemDropSystem.cs

@@ -0,0 +1,146 @@
+using Events;
+using Items;
+using UnityEngine;
+using UnityEngine.AddressableAssets;
+using Zenject;
+using Entity = Unity.Entities.Entity;
+
+namespace DefaultNamespace
+{
+	public class ItemDropSystem : InjectableComponentSystem
+	{
+		[Inject] private readonly ItemContainerFactory itemContainerFactory;
+
+		protected override void OnSystemUpdate()
+		{
+			Entities.WithNone<AssetReferenceData<ItemPrefab>>()
+				.ForEach(
+					(Entity entity, ref ItemDropEvent drop) =>
+					{
+						PostUpdateCommands.AddSharedComponent(
+							entity,
+							new AssetReferenceData<ItemPrefab>(Addressables.LoadAssetAsync<ItemPrefab>(drop.Item.Item.ToString())));
+					});
+
+			Entities.ForEach(
+				(Entity entity, AssetReferenceData<ItemPrefab> itemPrefab, ref ItemDropEvent drop) =>
+				{
+					if (!itemPrefab.Operation.IsValid)
+					{
+						PostUpdateCommands.DestroyEntity(entity);
+					}
+					else if (itemPrefab.Operation.IsDone)
+					{
+						var pos = drop.Pos;
+						var dropInventory = drop.Inventory;
+						var dropItem = drop.Item;
+						var dropVelocity = drop.Velocity;
+
+						if (EntityManager.Exists(drop.Inventory))
+						{
+							var inventory = EntityManager.GetBuffer<Slot>(drop.Inventory);
+
+							Slot ItemModification(Slot slot, bool set)
+							{
+								if (set)
+								{
+									slot.Item = dropItem;
+								}
+								else
+								{
+									slot.Item.Amount += dropItem.Amount;
+									slot.Item.Item = dropItem.Item;
+								}
+
+								PostUpdateCommands.DestroyEntity(entity);
+								PostUpdateCommands.PostEntityEvent(EntityManager, dropInventory, new InventoryDirtyEventData());
+								return slot;
+							}
+
+							//put in specific empty slot or combine with existing item in that slot
+							if (drop.ToSlot > 0 && drop.ToSlot < inventory.Length)
+							{
+								var toSlotData = inventory[drop.ToSlot];
+								if (CanDrop(toSlotData, itemPrefab.Operation.Result) &&
+								    (!toSlotData.HasItem() || toSlotData.Item.Item == dropItem.Item))
+								{
+									inventory[drop.ToSlot] = ItemModification(toSlotData, !toSlotData.HasItem());
+									return;
+								}
+							}
+
+							//combine with existing item
+							if (inventory.NativeFirstOrOptional(slot => slot.Item.Item == dropItem.Item)
+							    .NativeModify(s => ItemModification(s, false)))
+							{
+								return;
+							}
+
+							//move item in destination slot to slot drag came from if possible and occupy new slot with new item
+							if (drop.ToSlot > 0 && drop.ToSlot < inventory.Length)
+							{
+								var toSlotData = inventory[drop.ToSlot];
+								if (CanDrop(toSlotData, itemPrefab.Operation.Result) && drop.FromSlot >= 0 && drop.FromSlot < inventory.Length)
+								{
+									var fromSlotData = inventory[drop.FromSlot];
+									if (!fromSlotData.HasItem())
+									{
+										//todo check for slot compatibility
+										fromSlotData.Item = toSlotData.Item;
+										inventory[drop.FromSlot] = fromSlotData;
+										inventory[drop.ToSlot] = ItemModification(toSlotData, true);
+										return;
+									}
+								}
+							}
+
+							//put in free slot
+							if (inventory.NativeFirstOrOptional(slot => !slot.HasItem() && CanDrop(slot, itemPrefab.Operation.Result))
+							    .NativeModify(s => ItemModification(s, true)))
+							{
+								return;
+							}
+
+							//drop on ground near inventory
+							if (EntityManager.HasComponent<Rigidbody2D>(drop.Inventory))
+							{
+								pos = EntityManager.GetComponentObject<Rigidbody2D>(drop.Inventory).position;
+							}
+						}
+
+						itemContainerFactory.Create(itemPrefab.Operation.Result, dropItem.Item).Completed += asyncOperation =>
+						{
+							var rigidbody = asyncOperation.Result.GetComponent<Rigidbody2D>();
+							rigidbody.position = pos;
+							rigidbody.velocity = dropVelocity;
+						};
+
+						PostUpdateCommands.DestroyEntity(entity);
+					}
+				});
+		}
+
+		private bool CanDrop(Slot slot, ItemPrefab prefab)
+		{
+			switch (slot.Type)
+			{
+				case SlotType.None:
+					return true;
+
+				case SlotType.RangedWeapon:
+					return prefab is RangedWeaponItem;
+
+				case SlotType.MeleeWeapon:
+					return false;
+
+				case SlotType.Grenade:
+					return prefab is GrenadeItem;
+
+				case SlotType.Health:
+					return prefab is IHealItem;
+			}
+
+			return false;
+		}
+	}
+}